Monday, August 11, 2008

Twenty-six seastars (Protoreaster nodosus) from Cyrene Reefs were adopted by individuals as well as groups during the two-day event Be a Star! Adopt a Star!, International Year of the Reef on 8-9 August 2008.

Thank you for your generous donations.

Star Trackers would like to thank Vyna (top) and November (bottom), who were there at the booth till the stars shine (pun intended ;p).

Star Trackers were featured in the newspaper, My Paper on 11 August 2008. Thank you Koh Soo May for the interview.

MyPaper, 11 August 2008, Page 34.

Translation:

We all have a name and IC!

Two days ago, 24 local seastars were each given a name, becoming unique stars in the ocean.

These seastars, belong to a species commonly as the "Knobbly Seastar" as well as the "Chocolate Chip Seastar", were adopted by the public for a minimum sum of $50 donation at the International Year of the Reef event.

These seastars are not only unique in name but are also unique in the number and arrangement of knobs on the body surface.

Twenty-four knobbly seastars and at least 162 other individuals currently inhabit a local southern reef known as Cyrene Reefs. They can have their own "IC" (Identification Card) due to the hard work of two young men.

Since May this year, Chim Chee Kong (31 years old, research assistant) and Tan Sijie (26 years old, education and public relations officer) have visited Cyrene Reefs six times, took photographs and measurements for each seastar.

They have taken 220 photographs, of which 186 were recognised as individuals, including 55 juveniles.

Most of the seastars have five arms, although a few have only four arms, some of which were due to injury. In addition, the body may be of different colours, which consist of different shades of red, brown, beige etc.

The Knobbly Seastar is a locally endangered animal and the juveniles of this species are rare. This research project is extremely important to Chim Chee Kong and Tan Sijie, as it helps Singaporeans to better understand that we have these "lucky stars".

Two people started "Star Chasing" in May this year

Chim Chee Kong is a research assistant with the Tropical Marine Science Institute and Tan Sijie is a education and public relations officer with the Raffles Museum of Biodiversity Research. Both have strong interests in marine life.

Chim Chee Kong said "Seastars are charismatic animals, as demonstrated by their presence in many advertisements that promote the tropical island feel. Nonetheless, many do not know that Singapore has seastars, and related research are also few."

Chim Chee Kong and Tan Sijie started "star chasing" in May this year at Terembu Pandan, which is one of the reef of Cyrene Reefs.

Cyrene Reefs have two other smaller reefs.

They said that even though the Knobbly Seastar is also found at local sites such as Pulau Semakau, Chek Jawa and Changi Beach, the number of individuals are not as many as in Cyrene Reefs, and that is the reason why the ecology of the Knobbly Seastar population at Cyrene Reefs is worth investigating. "Although the Knobbly Seastar was classified as endangered in 1994, Cyrene Reefs is inhabitated by a large number of adults as well as juveniles, and is possibly the only sustainable population that remains locally.

Because Cyrene Reefs is submerged by 3m of water during high tides, they can only survey during low tides, with the help of boatmen.

They hope to have a long-term study on individuals regarding their growth rates, movements, ontogenetic change in morphology etc.

MyPaper, 11 August 2008, Page 35.

Translation:

Recording, Touching

Recording is often the touching action of people who cares.

Because of the hope not to let things die out by themselves, because of the fear that precious things and feelings be forgotten, thus the need for recording.

We record histories, sceneries, feelings, and daily things that happen around us, they chose to record seastars.

Two young men with a passion for marine life, tirelessly went to our country's southern reef in search of a species of seastar (Knobbly Seastar), took photographs and measurements of each seastar they encounter, provide each with an identification code, such that they are no longer just a population of seastars but are unique individuals.

A talk on the knobbly seastar will be held on 9 August 2008, 11.30 am, by the Star Trackers team. This is just one of the many exciting events during the Reef Celebrations! launch of IYOR (International Year of the Reef) in Singapore. A good way to celebrate National Day. ;)

Wednesday, July 2, 2008

A total of 220 photographs of the knobbly seastar (Protoreaster nodosus) were taken by the Star Trackers, Lin Juanhui and Lim Swee Cheng during six field trips to Cyrene Reef in May (8, 9 & 23) and June (6, 8 & 23) 2008.

Based on a recognition technique, these photographs belong to 186 individuals.

Measurements taken from 123 individuals showed that 45% of them are juveniles (seastar with minor radius less than 30 mm).

Adults were found in seagrass beds as well as sandy bottoms but juveniles were encountered only in seagrass beds.

These results reaffirm the observation in 14 May 2008 that Cyrene Reef is an extremely important habitat for the locally endangered seastar. This is a large population, which is likely to contain a much larger number of individuals than the 186 recorded so far, as the reef is yet to be surveyed intensively. The high proportion of juveniles is also exceptional. There are at least seven populations in Singapore but none of them appears to be as sustainable as the one at Cyrene Reef. The seagrass bed seems to be especially important to the juveniles. This microhabitat probably serve as recruitment, feeding and refuge grounds for the seastars. The charming seastar and the ecologically important seagrass beds deserve more attention in research.

Saturday, May 17, 2008

Abundance, Spatial Distribution, and Size Structure of the Sea Star Protoreaster nodosus in Palau, with Notes on Feeding and Reproduction

Scheibling, R. E. & Metaxas, A., 2008.

Bulletin of Marine Science 82(2): 221-235

Abstract

Protoreaster nodosus (Linnaeus, 1758) is a common sea star in shallow sand and seagrass habitats in the tropical Indo-pacific region. It has been extensively harvested as an ornament, but little is known of its biology and ecology. We quantitatively sampled populations at five sites in palau to obtain baseline information on abundance, spatial distribution, and population structure of this species in areas unaffected by human depredation. Density on sand bottoms ranged from 4 to 32 individuals 100 m-2 and biomass from 3.1 to 20.7 kg 100 m-2. Population size estimates at two locations were 100 and 630 individuals. Mean size (radius) of individuals ranged from 14 to 16 cm among populations, and was negatively related to density. Density was greatest in a seagrass bed (51 individuals 100 m-2, 12.3 kg 100 m-2) where the population was composed of juveniles (8-12 cm). Spatial distribution of sea stars in each population was random, as indicated by nearest-neighbor distance. Manipulations of density and spatial distribution, performed by removing or by adding and centrally aggregating individuals in circular plots (78.5 or 314 m2), showed that sea stars reestablish pre-manipulation densities and nearest-neighbor spacing within 2-5 d. Protoreaster nodosus feeds on meiobenthos and microbial/microalgal films by extra-oral ingestion of sediments and seagrass. The incidence of daytime feeding is generally high (> 60% of individuals), suggesting these sea stars are important consumers and bioturbators in sedimentary habitats. Synchronous spawning occurred at full moon (in May) in the laboratory, yielding planktotrophic larvae.

These photographs were captured after Tanjung Chek Jawa recovered from a mass death event that occurred in early 2007.Did other individuals survived this natural disaster? This question can be answered if photographs of individuals captured before and after the event are compared. If you have such photographs, please send them to chimck@yahoo.com.

Friday, May 16, 2008

Juveniles of the knobbly seastar (Protoreaster nodosus) are known to be rare in Singapore waters (Lane and Vandenspiegel 2003). The first visual documentation of a juvenile knobbly seastar is perhaps a posting in the blog of the Blue Waters Volunteers on 23 August 2005. The find happened during a ReefWalk activity at Kusu Island. Ever since juveniles were encountered at Cyrene Reef on 21 April 2007 by TeamSeagrass, recruitments of knobbly seastars were also observed at Pulau Semakau, Labrador Nature Reserve and Changi Beach.

The short population census conducted at Cyrene Reef on 8 and 9 May 2008 revealed that there are at least 62 individual knobbly seastars (Protoreaster nodosus) at the intertidal habitat. This is perhaps the largest Protoreaster population ever documented in Singapore. The population size is likely to be much larger than estimated as the two surveys were carried out on only a small (~20% of total area) intertidal area of Cyrene Reef. In addition, the population contained a wide range of body size (minor radius: 21-56 mm). There were at least 12 juveniles, which are seastars with minor radius less than 30 mm. The presence of juveniles, subadults and adults indicated that there is a healthy level of recruitment at Cyrene Reef. This habitat may be the only sustainable population of knobbly seastars left in Singapore today.

Tuesday, May 13, 2008

On 9 May 2008, a total of 45 knobbly seastar (Protoreaster nodosus) individuals were sighted at Cyrene Reef. Twelve of these were first encountered on 8 May 2008. Photographs of 33 'new' individuals are given below. Our recognition programme indicated that there are at least 62 individual seastars on this intertidal reef.